1. Field of the Invention
The invention relates to integrated circuits and somewhat more particularly to integrated circuits having a semiconductor substrate comprised of silicon in which and on which electrical components defining the circuit are produced and having contact interconnect levels comprised of an aluminum/silicon alloy.
2. Prior Art
Integrated semiconductor circuits with aluminum/silicon interconnect levels having an intermediate layer composed of titanium, which is utilized for attaining thermally similar characteristics (a so-called thermal match) between the conductive metal layer and the silicon oxide in order to increase device reliability and loadability are known. For example, see H. Murrmann, "Modern Bipolar Technology For High Performance ICs", Siemens Forschung-und Entwicklungsberichten (Siemens Research and Development Reports), Vol. 5, No. 6, (1976) pages 353-359.
Intermediate layers composed of titanium/tungsten which are also utilized for attaining a thermal match are described by P. B. Ghate and I. C. Blair in Thin Solid Films, Vol. 55, (1978) pages 113-123.
It can be derived from a report published by I. Ames, F. d'Heurle and R. Horstmann in IBM J. Res. Develop., Vol. 14, (1970) pages 461-463 that electromigration phenomena of material in aluminum films can reduced by the addition of 4% copper to the aluminum.
Extremely reliable interconnects can be fabricated from gold with intermediate layers composed of titanium and platinum (see M. P. Lepselter, The Bell System Tech. J., Vol. 45, (1966) pages 233-253. It can also be derived from the afore-referenced article that stable, low-resistant contacts between metal and silicon in a contact hole can be attained by utilizing platinum silicide.
However, all of the foregoing metallizations require additional intermediate layers and, thus, additional process steps which cause considerable added expense and which can increase the reject rate during manufacture of integrated circuits.